Vol. 60, 2021
(update: 2021.01.21; 03.08)
Differential
Protein Metabolism and Regeneration in Gastrocnemius Muscles in
High-fat Diet Fed Mice and Pre-hibernation Daurian Ground Squirrels: A
Comparison between Pathological and Healthy Obesity
Xia Yan1,2,§,
Qiaohua Niu2,§, Xuli Gao1,2, Shenyang Shen2,
Nan He2, Huiping Wang1,2, Rongrong Fang2,
Yunfang Gao1,2,*, and Hui Chang1,2,*
doi:10.6620/ZS.2021.60-06
1Shaanxi
Key Laboratory for Animal Conservation, Northwest University, Xi'an,
710069, P.R. China. *Correspondence: E-mail: changhui@nwu.edu.cn
(Chang); gaoyunf@nwu.edu.cn (Y. Gao). Tel: +8615389060926. Fax: 029-88303572. E-mail: 2364348698@qq.com (Yan); 672622062@qq.com (X. Gao); wanghp@nwu.edu.cn (Wang)
2Key
Laboratory of Resource Biology and Biotechnology in Western China
(College of Life Sciences, Northwest University), Ministry of
Education, Xi'an, 710069, P.R. China. E-mail: 1906266475@qq.com (Niu);
2232856399@qq.com (Shen); 1059006214@qq.com (Fang)
§XY and QN contributed
equally to this work.
Received 27 May 2020 / Accepted 31 December 2020
Communicated by Pung-Pung Hwang
We
focused on pathological obesity induced by excessive fat intake
(nutritional obesity) in non-hibernator and healthy obesity due to
pre-hibernation (PRE) fat storage in hibernator to study the effects of
different types of obesity on skeletal muscle protein metabolism and
cell regeneration. Kunming mice were fed with high-fat diet for 3
months to construct a pathological obesity model. Daurian ground
squirrels fattened
naturally before hibernation were used as a healthy obesity model. Body
weight, adipose tissue wet weight, gastrocnemius muscle wet weight,
muscle fiber cross-sectional area (CSA) and fiber type distribution
were measured. The protein expression levels related to protein
degradation (MuRF-1, atrogin-1, calpain1, calpain2, calpastatin,
desmin, troponin T, Beclin-1, LC3-II), protein synthesis (P-Akt,
P-mTORC1, P-S6K1,
P-4E-BP1) and cell regeneration (MyoD, myogenin, myostatin) were
detected by Western blot. As a result, the body weight and adipose
tissue wet weight were both significantly increased in high fat obese
(OB) mice and pre-hibernation fat (PRE) ground squirrels. The muscle
wet weight, ratio of muscle wet weight to body weight, and muscle fiber
CSA were significantly decreased, while the percentage of MHC I fiber
isoform was significantly increased in gastrocnemius muscle of OB mice
compared with the control (CON) group. The protein expression levels of
P-Akt, P-mTORC1, P-4E-BP1 and myogenin were significantly decreased,
while those of calpain1, calpain2, MuRF-1 and myostatin were
significantly increased in the OB mice. In the ground squirrels, the
muscle wet weight, muscle fiber CSA and percentage of MHC I fiber
isoform all showed no change in the gastrocnemius muscle in the PRE
group compared with the summer active (SA) group. The protein
expression levels of P-Akt, P-mTORC1, P-S6K1 and MyoD were
significantly increased, while those of Beclin-1 and LC3-II were
significantly decreased in the PRE
ground squirrels. This study demonstrated that the decrease in protein
expression levels in the Akt/mTOR pathway (P-Akt, P-mTORC1 and
P-4E-BP1) and cell regeneration (myogenin) and the increase in protein
expression levels of the calpain pathway (calpain1 and calpain2) and
ubiquitin-proteasome pathway (MuRF-1) were involved in the mechanism of
muscle atrophy in gastrocnemius muscle of the pathologically obese
Kunming mice induced by high-fat diet. In contrast, the increased
protein expression levels of the Akt/mTOR pathway (P-Akt, P-mTORC1 and
P-S6K1) and cell regeneration (MyoD), and the decreased protein
expression levels of the autophagy lysosomal pathway (Beclin-1 and
LC3-II) were involved in the mechanism of anti-atrophy in gastrocnemius
muscle of the healthy obese ground squirrels fattened before
hibernation.
Key words: High-fat diet,
Pre-hibernation fattening, Protein metabolism, Cell regeneration,
Skeletal muscle atrophy.
Citation:
Yan X, Niu Q, Gao X, Shen S, He N, Wang H, Fang R, Gao Y, Chang H.
2021. Differential protein metabolism and regeneration in gastrocnemius
muscles in high-fat diet fed mice and pre-hibernation Daurian ground
squirrels: a comparison between pathological and healthy obesity. Zool
Stud 60:6.
doi:10.6620/ZS.2021.60-06.

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